Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Common Stock	Treasury Stock	Additional Paid-in Capital
Beginning balance at Dec. 31, 2018	$ 691,618	$ 528,027	$ (3,602)	$ 2,151	$ (56)	$ 165,098
Beginning balance, common stock (in shares) at Dec. 31, 2018				32,256,209
Beginning balance, treasury stock (in shares) at Dec. 31, 2018					(706)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	18,783	18,783
Other comprehensive income (loss)	(1,084)		(1,084)
Treasury shares purchased	(727)				$ (727)
Treasury shares purchased (in shares)					(8,496)
Shares and options issued under stock plans	1,919			$ 5	$ 250	1,664
Shares and options issued under stock plans (in shares)				73,823	3,006
Ending balance at Mar. 31, 2019	710,509	546,810	(4,686)	$ 2,156	$ (533)	166,762
Ending balance, common stock (in shares) at Mar. 31, 2019				32,330,032
Ending balance, treasury stock (in shares) at Mar. 31, 2019					(6,196)
Beginning balance at Dec. 31, 2019	743,667	590,921	(5,564)	$ 2,161	$ (18,069)	174,218
Beginning balance, common stock (in shares) at Dec. 31, 2019				32,405,796
Beginning balance, treasury stock (in shares) at Dec. 31, 2019					(203,879)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	19,768	19,768
Other comprehensive income (loss)	(2,905)		(2,905)
Treasury shares purchased	(891)				$ (891)
Treasury shares purchased (in shares)					(8,224)
Shares and options issued under stock plans	6,632			$ 3	$ 7,266	(637)
Shares and options issued under stock plans (in shares)				41,619	81,530
Ending balance at Mar. 31, 2020	$ 766,271	$ 610,689	$ (8,469)	$ 2,164	$ (11,694)	$ 173,581
Ending balance, common stock (in shares) at Mar. 31, 2020				32,447,415
Ending balance, treasury stock (in shares) at Mar. 31, 2020					(130,573)